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add stream folder with scan and scan-merge

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This commit is contained in:
Zach Dahl 2016-10-29 00:24:18 -05:00
parent db956d7194
commit db445a899d
4 changed files with 147 additions and 0 deletions
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26
stream/scan-merge.js Normal file
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//! adapted for mithril from flyd https://github.com/paldepind/flyd
'use strict'
var combine = require('../stream').combine
module.exports = function (tuples, seed) {
var streams = tuples.map(function (tuple) {
var stream = tuple[0]
if (stream._state.state === 0) stream(undefined)
return stream
})
var newStream = combine(function () {
var changed = arguments[arguments.length - 1]
streams.forEach(function (stream, idx) {
if (changed.indexOf(stream) > -1) {
seed = tuples[idx][1](seed, stream._state.value)
}
})
return seed
}, streams)
return newStream
}

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stream/scan.js Normal file
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//! adapted for mithril from flyd https://github.com/paldepind/flyd
'use strict'
var combine = require('../stream').combine
module.exports = function (reducer, seed, stream) {
var newStream = combine(function (s) {
return seed = reducer(seed, s._state.value)
}, [stream])
if (newStream._state.state === 0) newStream(seed)
return newStream
}

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stream/tests/index.html Normal file
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
</head>
<body>
<script src="../../module/module.js"></script>
<script src="../../ospec/ospec.js"></script>
<script src="../../util/stream.js"></script>
<script src="../../stream.js"></script>
<script src="../scan.js"></script>
<script src="../scan-merge.js"></script>
<script src="test-stream.js"></script>
<script>require("../../ospec/ospec").run()</script>
</body>
</html>

90
stream/tests/test-stream.js Normal file
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'use strict'
var o = require('../../ospec/ospec')
o.spec('stream', function () {
var prop
o.beforeEach(function () {
prop = require('../../stream')
})
o.spec('scan', function () {
var scan
o.beforeEach(function () {
scan = require('../scan')
})
o('defaults to seed', function () {
var parent = prop()
var child = scan(function (out, p) {
return out - p
}, 123, parent)
o(child()).equals(123)
})
o('accumulates values as expected', function () {
var parent = prop()
var child = scan(function (arr, p) {
return arr.concat(p)
}, [], parent)
parent(7)
parent('11')
parent(undefined)
parent({ a: 1 })
var result = child()
// deepEquals fails on arrays?
o(result[0]).equals(7)
o(result[1]).equals('11')
o(result[2]).equals(undefined)
o(result[3]).deepEquals({ a: 1 })
})
})
o.spec('scanMerge', function () {
var scanMerge
o.beforeEach(function () {
scanMerge = require('../scan-merge')
})
o('defaults to seed', function () {
var parent1 = prop()
var parent2 = prop()
var child = scanMerge([
[parent1, function (out, p1) {
return out + p1
}],
[parent2, function (out, p2) {
return out + p2
}]
], -10)
o(child()).equals(-10)
})
o('accumulates as expected', function () {
var parent1 = prop()
var parent2 = prop()
var child = scanMerge([
[parent1, function (out, p1) {
return out + p1
}],
[parent2, function (out, p2) {
return out + p2 + p2
}]
], 'a')
parent1('b')
parent2('c')
parent1('b')
o(child()).equals('abccb')
})
})
})